Based on “Game Score” it was the best start of the season, rating as a 93. Cliff Lee‘s three-hit shutout of the Nationals in mid-April had ranked as the top start at 92, with outings from Dan Haren, Tim Hudson, Ian Kennedy, and Jaime Garcia plus Verlander’s no-hitter close behind.

Shields struggled last season as his ERA ballooned to 5.18 and he led the league in hits, runs, and homers allowed. However, his secondary numbers were still very strong with a 187/51 K/BB ratio in 203 innings and advanced pitching metrics like xFIP showed that an unsustainably high batting average on balls in play was largely to blame for the struggles. In fact, last season his xFIP was 3.55, which ranked seventh in the league.

He’s been even better this year, as yesterday’s gem brought his xFIP down to 2.68, and Shields’ batting average on balls in play has dropped from .341 to .249. In terms of turning balls in play into outs behind Shields the Rays’ defense has gone from one of the worst in baseball to one of the best in baseball, which along with excellent pitching equals a 2.00 ERA and MLB-leading three complete games.

To quibble, but BABIP has nothing to do with xFIP (or FIP for that matter). The formula for FIP as defined by fangraphs is:

((13*HR)+(3*(BB+HBP-IBB))-(2*K))/IP + constant (based on league ERA)

xFIP merely normalizes HR rate per league average. Last year he struggled because he had an abnormally high BABIP, high walk rate and high HR rate. Putting that all together can equal big innings. This year it’s a really low BABIP that will probably correct itself if not this year than next.

I appreciate the comment, but you’re wrong. xFIP (and FIP) assume (indirectly) a standard BABIP by focusing only on things a pitcher can control. If a pitcher has a .350 BABIP, their xFIP will be significantly lower. That’s one of the primary benefits of the statistic. If all it did was normalize home run rate, the stat would be much different.

per fangraphs:
“In other words, pitchers have little control over balls in play, so a better way to assess a pitcher’s talent level is by looking at things a pitcher can control: strikeouts, walks, hit by pitches, and homeruns.”

None of those have any influence on BABIP, since HR aren’t in play they aren’t counted.

churchoftheperpetuallyoutraged - May 23, 2011 at 2:16 PM

If all it did was normalize home run rate, the stat would be much different.

That’s the x part of xFIP, normalized HR rate.

Aaron Gleeman - May 23, 2011 at 2:19 PM

None of those have any influence on BABIP, since HR aren’t in play they aren’t counted.

You’re missing the point. By judging a pitcher on only strikeouts and walks, xFIP and FIP are essentially using a standard BABIP rather than actual BABIP.

That’s the x part of xFIP, normalized HR rate.

Trust me, I understand. I co-created the site on which xFIP was first introduced. But normalizing home run rate is not all the statistic accomplishes. It evaluates based on SO, BB, and HR, which in turn normalizes BABIP. xFIP showed that Shields was pitching better than his ERA suggested because of HR rate, but also because of BABIP.